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St. Michael’s-based researchers take part in new studies evaluating CPR and drugs after sudden cardiac arrest

Toronto, February 9, 2012

By Leslie Shepherd

TORONTO, Ont., Feb. 9, 2010 – Researchers based at St. Michael’s Hospital are participating in two new large North American clinical trials sponsored by the U.S. National Institutes of Health to evaluate treatments for out-of-hospital cardiac arrest.

One trial will compare standard cardiopulmonary resuscitation (CPR), which includes a combination of chest compressions and pauses for breathing, with continuous chest compressions (CCC) and no pause before breathing.

The other trial will compare treatment with the drug amiodarone, another drug called lidocaine or a placebo in participants with shock-resistant ventricular fibrillation, a condition in which the heart beats chaotically instead of pumping blood.

Dr. Laurie Morrison instructing CPR.

The majority of the 45,000 people who have cardiac arrest in Canada each year are assessed by emergency medical service (EMS) providers. During a cardiac arrest, the heart stops beating and unless it is restarted within minutes, the person usually dies.

Although immediate CPR can be lifesaving, more than 90 percent of people who experience a cardiac arrest outside of a hospital die before reaching a hospital or soon thereafter.

"Increasing survival rates for people who experience out-of-hospital cardiac arrest is a major public health goal," said Dr. Susan B. Shurin, acting director of the NIH's National Heart, Lung, and Blood Institute, which is the lead U.S. sponsor of the studies. "These new trials could provide critical insight about which resuscitation efforts are most effective for cardiac arrest."

One of three Canadian sites chosen to participate in the studies is Rescu, based at St. Michael's Hospital. Rescu is part of the Resuscitations Outcomes Consortium (ROC), a large, multinational research collaboration of 10 sites across the United States and Canada, studying how promising new tools and treatments can improve survival rates among people who suffer cardiac arrest or life-threatening traumatic injury outside of hospitals.

"The Canadian Institutes of Health Research are proud to support this important research collaboration between Canada and the USA," said Dr. Jean Rouleau, scientific director of the CIHR Institute of Circulatory and Respiratory Health. "The ROC group has produced invaluable information about this critical period of treatment – information that will increase survival rates for Canadians, Americans, and people throughout the world."

"Findings to date from ROC trial have tripled survival rates in their test communities," said Bobbe Wood, president, Heart and Stroke Foundation of Canada. "The potential is huge. Research into the most effective resuscitation methods to improve bystander chest compression rates, the quality of CPR, and EMS response times could save so many more Canadian lives every year."

The CCC trial will compare how many people survived until they are discharged from hospital rates for two CPR approaches. People experiencing cardiac arrest will be randomly assigned to receive continuous chest compressions or standard CPR by emergency responders. Standard CPR, the approach recommended by the American Heart Association for use by emergency responders, includes chest compressions with short pauses for assisted breathing. This approach has been called into question by emerging data suggesting that stopping chest compressions to provide assisted breathing interrupts overall blood flow, which may lower survival.

Previous studies have shown that people who suffer cardiac arrest outside of the hospital and are treated by bystanders are more likely to survive when given compressions alone. In 2010, the AHA adopted new guidelines that recommended continuous chest compressions only for bystanders.

The CCC trial will enroll up to 23,600 participants at eight major regional locations across the U.S. and Canada.

The ALPS study -- Amiodarone, Lidocaine, or neither (Placebo) for Out-Of-Hospital Cardiac Arrest Due to Ventricular Fibrillation or Tachycardia -- will determine whether amiodarone or lidocaine improves survival-to-hospital-discharge rates for participants with shock-resistant ventricular fibrillation. Participants will receive one or the other drug or a placebo.

About 25 percent of cardiac arrests are due to ventricular fibrillation. When shock treatment with a defibrillator fails to restore normal heart rhythm during ventricular fibrillation, medications such as amiodarone or lidocaine are often given, but their effectiveness in improving survival is unknown.

The ALPS trial will enroll up to 3,000 participants at nine locations across North America.

Lead investigator for the University of Toronto site, Dr Laurie Morrison of Rescu, St Michael’s Hospital, suggests these studies address the lack of science on how best to perform CPR and which drugs are effective. The paramedics and firefighters in all the participating regions are making a valuable contribution to defining the science of resuscitation and contributing to survival which is an essential contribution.

The NHLBI is the lead U.S. government sponsor for both of the new studies, and the U.S. Army Medical Research and Materiel Command is a co-sponsor. Additional funding is provided by the Canadian Institutes of Health Research, the Heart and Stroke Foundation of Canada, the Defense Research and Development Canada, and the American Heart Association.

About St. Michael's Hospital

St. Michael's Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in more than 23 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, and care of the homeless are among the Hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Center, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.